It is common for images to appear as a sequence of images, for example, as video or motion pictures. The display of the sequence of images in rapid succession may be used to give the impression of continuous fluid motion. However, as with the processing of any signal, the processing of signals representing image sequences generally introduces noise into the image sequences. Such processing may include recording, storing, manipulating, transmitting, and displaying of the image sequences. For example, noise may result from weak television signals, a poor cable television connection, aging and handling of motion picture film, or during playback of a videocassette tape in a videocassette recorder. Thus, as more processing is performed on an image sequence, the noise introduced into the image sequence accumulates. Consequently, the image sequence displayed is not a “perfect copy” of the original image sequence, but is progressively degraded as the image sequence is processed.
Thus, it is desirable to reduce the noise in the image sequence. Moreover, image sequences are typically processed at a high rate, for example 24 or 30 frames per second. Each frame constitutes a separate image may include thousands or millions of pixels. Thus, if processing of each frame or each pixel is computationally complex, the amount of processing power needed may easily become overwhelming. Thus, a technique is needed which provides high quality image sequences by providing effective noise reduction, but which can be implemented using a few simple numerical operations.